Hiding behind a car in a gun fight may be your only option. But even though they may appear to be formidable barriers, cars are not impenetrable objects.
BALLISTICS
A 9mm bullet can pass through six interior walls before it loses its killing power. When it comes to cars, that same bullet can easily pass through a car door, and still have energy to kill. Passing through both doors at a killing capacity is more a matter of ammo type. Depending on the type of ammo and obstructions along the way, a 9mm bullet can completely penetrate both doors and even the wheels.
So it needs to be stated here, if you are inside a car in a gun fight, get out! If you are outside, using the car as cover, you still run the risk of catching a round. I won’t be waiting to witness rounds exit from my cover before I move off the X.
ENGINE BLOCK
The only sure thing about using a car for cover is bullets generally cannot pass through engine blocks. Leaving ultra powerful rifle rounds out of the conversation, the engine block is the best area of a car to find cover.
But even this tactic is not without its risks. Engine blocks do not consume the entire engine space. In fact, on smaller cars, they may only be able to protect your upper thoracic region (heart, lungs, etc.) or your head. Catching a round in the leg or arm can be a fight-ender for you.
EXPOSURE
Regardless of where you seek cover around a vehicle, you are still an open target. Tires don’t stop bullets, you may as well hide behind the windshield. You are still very exposed albeit somewhat blocked from view.
At distance, however, your visibility can be dramatically reduced by eliminating the ability of an attacker to find you by seeking cover behind a tire. Doing so at the front of a vehicle, behind the engine block, reduces your risk even more. But none of this really works at close range.
SHORT DISTANCE ENCOUNTERS
When caught in a close range attack, it is best to put more than a car between you and the attacker. The more distance and cars you can put between you and their gun, the less likely you will be shot.
Defensively speaking, it is quite difficult to hit a moving target. Even more difficult to hit someone dodging between cars. If you have an opportunity to put space between you and the attacker, even if you are armed, that could be the decision that saves your life.
Staying in the fight may seem like the right thing to do, and killing the bad guy before he does harm to anyone else sounds heroic, but you are no good to anyone if you are dead. Defensive gun fighting is about managing the situation to your advantage, not thrusting yourself into a volley of lead.